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| United States Patent |
5,324,788
|
|
Kuo
|
June 28, 1994
|
Thermosetting coating compositions
Abstract
Provided are enamel compositions and water-borne enamel compositions
comprising phenol functionalized vinyl polymers and crosslinking agents
such as aminoplasts, e.g., alkylated melamine-formaldehyde condensates.
The coatings produced from such compositions possess excellent acid-etch
resistance, solvent resistance, hardness, and gloss. The compositions of
the present invention are thus particularly useful for automotive,
appliance and machinery coatings.
| Inventors:
|
Kuo; Thauming (Kingsport, TN)
|
| Assignee:
|
Eastman Kodak Company (Rochester, NY)
|
| Appl. No.:
|
054481 |
| Filed:
|
April 30, 1993 |
| Current U.S. Class: |
525/329.5; 524/564; 525/333.3; 525/384; 526/326 |
| Intern'l Class: |
C08F 008/12; C08F 218/00; C08G 012/32 |
| Field of Search: |
525/329.5,333.3,384
526/326
524/564
|
References Cited
U.S. Patent Documents
| 4137279 | Jan., 1979 | Smith et al. | 525/411.
|
| 4678843 | Jul., 1987 | Elmore et al. | 525/329.
|
| 4857601 | Aug., 1989 | Gupta | 525/344.
|
| 4898916 | Feb., 1990 | Gupta | 525/355.
|
| 5106651 | Apr., 1992 | Tyger et al. | 427/54.
|
| Foreign Patent Documents |
| 0419088A1 | Mar., 1991 | EP.
| |
| 0466359A2 | Jan., 1992 | EP.
| |
Other References
Masao Kato, J. of Polymer Science, Part A-1, vol. 7, 2405-2410 (1969).
Masao Kato, J. of Polymer Science, Part A-1, vol. 7, 2175-2184 (1969).
J. M. J. Frechet et al., Macromolecules, 1991, 24, 1746-1754.
Paolo Ferruti and Angelino Fere, J. of Polymer Science, Part A-1, vol. 9,
3671-3673 (1971).
|
Primary Examiner: Michl; Paul R.
Assistant Examiner: Merriam; Andrew E. C.
Attorney, Agent or Firm: Graves, Jr.; Bernard J.
Claims
I claim:
1. An enamel composition comprising
(I) about 25 to about 65 wt %, based on the total weight of components (I),
(II) and (III), of a phenol functionalized vinyl polymer having a number
average molecular weight of about 1000 to about 50,000 and a weight
average molecular weight of about 5,000 to about 100,000, said phenol
functionalized vinyl polymer prepared by polymerization of the following
vinyl components:
(a) about 5 to about 80 wt % of a 4-acyloxystyrene compound of Formula A,
##STR11##
wherein R is selected from hydrogen, C.sub.1 -C.sub.6 -alkyl, C.sub.1
-C.sub.6 -alkoxy, C.sub.5 -C.sub.7 -cycloalkyl, aryl, aryloxy, C.sub.1
-C.sub.6 -alkylamino and arylamino; R.sub.1 is selected from hydrogen,
C.sub.1 -C.sub.6 -alkyl, C.sub.1 -C.sub.6 -alkoxy and halogen; R.sub.2 is
hydrogen or methyl; and R.sub.3 is a covalent bond or is selected from a
group of the formulae --(CHR').sub.n --, --O--, --S--, --C(O)--,
--OC(O)--, --C(O)O--, --C(O)--O(CH.sub.2).sub.n --O--C(O)--, and
--NH--C(O)--, wherein R' is hydrogen or a group of the formula
R--C(O)O-phenyl- or R--C(O)O-naphthyl; each R" is hydrogen or both R" are
taken together to form a group of the formula
##STR12##
and n is an integer of from 1 to 10; (b) about 0 to about 50 wt % of a
styrene compound of Formula B, and/or an acylated vinyl alcohol of Formula
C,
##STR13##
R, R.sub.1 and R.sub.2 are as defined above; (c) about 20 to about 90 wt
% of an acrylate monomers of Formula D,
##STR14##
wherein R.sub.2 is as defined above and R.sub.4 is selected from C.sub.1
-C.sub.12 -alkyl; C.sub.5 -C.sub.7 -cycloalkyl; C.sub.1 -C.sub.12 -alkyl
substituted by one or more groups selected from C.sub.1 -C.sub.6 -alkoxy,
C.sub.5 -C.sub.7 -cycloalkyl, hydroxy, acetoacetoxy, aryl, furyl,
tetrahydofuryl and --N(R.sub.5)R.sub.6 wherein R.sub.5 and R.sub.6 are
independently selected from C.sub.1 -C.sub.6 -alkyl or hydrogen; and
(d) about 0 to about 20 wt % of acrylic acid and/or methacrylic acid,
said polymerization followed by transesterification with an alcohol to
convert the acyloxyphenyl groups on the polymer to the phenol
functionalized vinyl polymer;
(II) about 5 to about 20 wt % of an amino crosslinking agent, based on the
total weight of (I), (II) and (III); and
(III) about 20 to about 70 wt % of an organic solvent, based on the total
weight of (I), (II) and (III).
2. The enamel composition of claim 1, wherein R.sub.3 is a covalent bond or
is selected from a group of the formulae --(CHR').sub.n --, --O--,--S--,
--C(O)--, and --OC(O)--, wherein R' is hydrogen or a group of the formula
R--C(O)-phenyl- and n is an integer of from 1 to 10.
3. The enamel composition of claim 1, wherein (a) is selected from the
group consisting of 2-acetoxystyrene, 3-acetoxystyrene, and
4-acetoxystyrene.
4. The enamel composition of claim 1, wherein (b) is selected from the
group consisting of styrene, vinyl acetate, and vinyl butyrate.
5. The enamel composition of claim 1, Wherein (b) is styrene.
6. The enamel composition of claim 1, wherein (c) is selected from the
group consisting of methyl methacrylate, butyl acrylate, isobutyl
methacrylate, lauryl methacrylate, 2-ethylheyl acrylate, 2- hydroxyethyl
methacrylate, acetoacetoxypropyl methacrylate, acetoacetoxyethyl
methacrylate, and glycidyl methacrylate.
7. The enamel composition of claim 1, wherein (c) is methyl methacrylate or
butyl acrylate or a mixture thereof.
8. The enamel composition of claim i, wherein
(a) is 4-acetoxystyrene;
(b) is styrene;
(c) is methyl methacrylate or butyl acrylate or a mixture thereof; and
(d) is acrylic acid or methacrylic acid or a mixture thereof.
9. The enamel composition of claim 1, wherein the cross-linking agent is a
compound having a plurality of --N(CH.sub.2 OR.sup.3).sub.2 functional
groups, wherein R.sup.3 is C.sub.1 -C.sub.4 alkyl.
10. The enamel composition of claim 1, wherein the crosslinking agent is
selected from compounds of the following formulae, wherein R.sup.3 is
independently C.sub.1 -C.sub.4 alkyl:
##STR15##
11. The enamel composition of claim 1, wherein the crosslinking agent is
selected from hexamethoxymethylmelamine, tetramethoxymethylbenzoguanamine,
tetramethoxymethylurea, and mixed butoxy/methoxy substituted melamines.
12. A water-borne enamel composition comprising
(I) about 25 to about 65 wt %, based on the total weight of components (I),
(II), (III), (IV), and (V), of a phenol functionalized vinyl polymer
having a number average molecular weight of about 1000 to about 50,000 and
a weight average molecular weight of about 5,000 to about 100,000, said
phenol functionalized vinyl polymer prepared by polymerization of the
following vinyl components:
(a) about 5 to about 80 wt % of a 4-acyloxystyrene compound of Formula A,
##STR16##
wherein R is selected from hydrogen, C.sub.1 -C.sub.6 -alkyl, C.sub.1
-C.sub.6 -alkoxy, C.sub.5 .C.sub.7 -cycloalkyl, aryl, aryloxy, C.sub.1
-C.sub.6 -alkylamino and arylamino; R.sub.1 is selected from hydrogen,
C.sub.1 -C.sub.6 -alkyl, C.sub.1 -C.sub.6 -alkoxy and halogen; R.sub.2 is
hydrogen or methyl; and R.sub.3 is a covalent bond or is selected from a
group of the formulae --(CHR').sub.n --, --O--, --S--, --C(O)--,
--OC(O)--, --C(O)O--, --C(O)--O(CH.sub.2).sub.n --O--C(O)--, and
--NHC(O)--, wherein R' is hydrogen or a group of the formula
R--C(O)O-phenyl-, or R--C(O)O-naphthyl; each R" is hydrogen or both R" are
taken together to form a group of the formula
##STR17##
and n is an integer of from 1 to 10; (b) about 0 to about 50 wt % of
compound of Formula B, and/or an acylated vinyl alcohol of Formula C,
##STR18##
wherein R, R.sub.1 and R.sub.2 are as defined above; (c) about 20 to
about 90 wt % of an acrylate monomer of Formula D,
##STR19##
wherein R.sub.2 is as defined above and R.sub.4 is selected from C.sub.1
-C.sub.12 -alkyl; C.sub.5 -C.sub.7 -cycloalkyl; C.sub.1 -C.sub.12 -alkyl
substituted by one or more groups selected from C.sub.1 -C.sub.6 -alkoxy,
C.sub.5 -C.sub.7 -cycloalkyl, hydroxy, acetoacetoxy, aryl, furyl,
tetrahydofuryl and --N(R.sub.5)R.sub.6 wherein R.sub.5 and R.sub.6 are
independently selected from C.sub.1 -C.sub.6 -alkyl or hydrogen; and
(d) about 0 to about 20 wt % of acrylic acid and/or methacrylic acid,
said polymerization followed by tranesterification with an alcohol to
convert the acyloxyphenyl groups on the polymer to the phenol
functionalized vinyl polymer (I);
(II) about 0 to about 30 wt % of a water-miscible organic solvent, based on
the total weight of I, II, III, IV and (V);
(III) about 30 to about 70 wt % of water, based on the total weight of (I),
(II), (III), (IV) and (V);
(IV) about 5 to about 20 wt % of a crosslinking agent, based on the total
weight of (I), (II), (III), (IV) and (V);
(V) about 0.5 to about 3 wt % of an amine, based on the total weight of
(I), (II), (III), (IV), and (V), wherein said amine is reacted directly
with said vinyl polymer (I).
13. The water borne enamel composition of claim 12, wherein R.sub.3 is a
covalent bond or is selected from a group of the formulae --(CHR').sub.n
--, --O--, --S--, --C(O)--, and --OC(O)--, wherein R' is hydrogen or a
group of the formula R--C(O)-phenyl- and n is an integer of from 1 to 10.
14. The water-borne enamel composition of claim 12, wherein (a) is selected
from the group consisting of 2-acetoxystyrene, 3-acetoxystyrene, and
4-acetoxystyrene.
15. The water-borne enamel composition of claim 12, wherein (b) is selected
from the group consisting of styrene, vinyl acetate, and vinyl butyrate.
16. The water-borne enamel composition of claim 12, wherein (b) is styrene.
17. The water-borne enamel composition of claim 12, wherein (c) is selected
from the group consisting of methyl methacrylate, butyl acrylate, isobutyl
methacrylate, lauryl methacrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl
methacrylate, and glycidyl methacrylate.
18. The water borne enamel composition of claim 12, wherein (c) is methyl
methacrylate or butyl acrylate or a mixture thereof.
19. The water borne enamel composition of claim 12, wherein (d) is acrylic
acid or methacrylic acid or a mixture thereof.
20. The water-borne enamel composition of claim 12, wherein
(a) is 4-acetoxystyrene;
(b) is styrene;
(c) is methyl methacrylate or butyl acrylate or a mixture thereof; and
(d) is acrylic acid or methacrylic acid or a mixture thereof.
21. The enamel composition of claim 12, wherein the cross-linking agent is
a compound having a plurality of --N(CH.sub.2 OR.sup.3).sub.2 functinal
groups, wherein R.sup.3 is C.sub.1 -C.sub.4 alkyl or hydrogen.
22. The water-borne enamel composition of claim 12, wherein the croslinking
agent is selected from compounds of the following formulae, wherein
R.sup.3 is independently C.sub.1 -C.sub.4 alkyl or hydrogen:
##STR20##
23. The water-borne enamel composition of claim 12, wherein the
crosslinking agent is selected from hexamethoxymethylmelamine,
tetramethoxymethylbenzoguanamine, tetramethoxymethylurea, and mixed
butoxy/methoxy substituted melamines.
24. A shaped or formed article coated with the cured composition of claim
1.
25. A shaped or formed article coated with the cured composition of claim
12.
Description
FIELD OF THE INVENTION
This invention belongs to the field of vinyl polymers. In particular, this
invention relates to phenol-functionalized vinyl polymers which are useful
as binders in enamel compositions.
BACKGROUND OF THE INVENTION
There is a need in the coatings industry for high strength, high modulus,
chemically resistant coatings. This invention is directed toward meeting
the above needs and the coatings described herein exhibit improvements in
one or more specific properties of acid resistance, pencil hardness,
solvent resistance, gloss, etc.
EP-A 466,359 discloses a process for preparing phenol functionalized
polymers by the polymerization of 4-acetoxystyrene and copolymerization of
4-acetoxystyrene and additional vinyl comonomers such as acrylates
followed by transesterification with an alcohol. The polymers are taught
to be useful as photoresist components for use in combination with UV,
X-ray and E-beam imaging systems. Similarly, U.S. Pat. No. 4,857,601
discloses a process for preparing copolymers of 4-acetoxystyrene and
dialkyl muconates or alkyl sorbates, followed by an alcohol or aqueous
treatment with acid or base to provide the final phenol functionalized
polymer.
U.S. Pat. No. 5,106,651 discloses a method for preparing coatings
consisting of applying a film forming composition containing an active
hydrogen-containing polymer and an aminoplast curing agent to form a
coated article. No phenol functionalization is disclosed and only
aliphatic hydroxy and carboxylic acid active hydrogen groups are
mentioned. Further, these compositions require an additional exposure to
UV radiation to produce enamels having good resistance to acid etching and
water spotting.
EP-A 419,088 discloses non liquid crystalline, ester phenol capped polymers
and such polymers cross-linked with aminoplast curing agents to give
enamel coatings. In these compositions, the phenol moiety is always linked
to the polymer through an ester group prepared by reacting polymers
containing aliphatic hydroxy groups with hydroxybenzoic acids. This
reference teaches that the polymers may be polyesters, alkyds, acrylics,
or epoxy resins.
Additional linear, high molecular weight, phenol functionalized polymers
have been prepared by polymerization of hydroxystyrenes in the presence of
cationic catalysts [Masao Kato, J. of Polymer Science, Part A-1, Vol. 7,
2405-2410 (1969)]. Also, hydroxystyrenes have been copolymerized with
other vinyl monomers such as acrylate esters in the presence of free
radical initiators to produce phenol functionalized polymers [Masao Kato,
J. of Polymer Science, Part A-1, Vol. 7, 2175-2184 (1969)]. Further,
phenol functionalized polymers have been produced by radical catalyzed
copolymerization of 4-(acetoxymethyl) styrene and
4-(t-butyloxycarbonyloxy) styrene followed by removal of the t
butyloxycarbonyl groups from the polymer (J.M.J. Frechet, et al.,
Macromolecules, 1991, 24, 1746-1754). Poly(4-hydroxystyrene) has also been
prepared from poly(4-vinylphenyl benzyl ether) followed by cleavage of the
benzyl ether groups on the polymer by hydrobromic acid (Paolo Ferruti and
Angelino Fere, J. of Polymer Science, Part A1, Vol. 9, 3671-3673 (1971)).
SUMMARY OF THE INVENTION
This invention provides novel enamel compositions comprising phenol
functionalized vinyl polymers and crosslinking agents such as aminoplasts,
e.g., alkylated melamine-formaldehyde condensates. The enamel coatings
produced from said enamel compositions have excellent acid-etch
resistance, solvent resistance, hardness, and gloss. The compositions of
the present invention are thus particularly useful for coating automotive,
appliance and machinery parts.
DETAILED DESCRIPTION OF THE INVENTION
This invention provides novel enamel compositions comprising phenol
functionalized vinyl polymers and crosslinking agents contained in organic
solvents or aqueous media (water borne) which provide enamel compositions
having excellent properties when cured. In addition, the enamels have
improved stability at room temperature.
The phenol functionalized vinyl polymers of the present invention are
characterized by the presence of phenol functional moieties
##STR1##
randomly present on the linear polymer chain. Other conventional and more
economical vinyl comonomers such as acrylates, methacrylates, styrenes,
etc. can be used to produce a major portion of the polymer backbone. The
phenol functionalized vinyl polymers are crosslinked by treating with
crosslinking agents, such as aminoplasts, to produce the thermosetting or
heat cured enamel coatings. Aminoplasts are aldehydes condensation
products of amines or amides, such as melamine. To provide the most
economical coating composition, it may be desirable to use only enough
phenol functional moieties to provide adequate crosslinking upon curing in
the presence of the aminoplast crosslinking agents.
To facilitate curing, the enamel compositions preferably contain acid
catalysts such as sulfonic acids, e.g., p toluenesulfonic acid,
dodecylbenzene sulfonic acid; acid phosphates, e.g., phenyl acid
phosphate, etc. The amount of catalyst present is preferably from about
0.05 to 5 percent based on the total weight of the binder, i.e., the
weight of the resin and crosslinker combined.
Thus, the present invention provides an enamel composition comprising
(I) about 25 to about 65 wt %, based on the total weight of components (I),
(II) and (III), of a phenol functionalized vinyl polymer having a number
average molecular weight of about 1000 to about 50,000 and a weight
average molecular weight of about 5,000 to about 100,000, said phenol
functionalized vinyl polymer prepared by polymerization of the following
vinyl components:
(a) about 5 to about 80 wt % of a 4-acyloxystyrene compound of Formula A,
##STR2##
wherein R is selected from hydrogen, C.sub.1 -C.sub.6 -alkyl, C.sub.1
-C.sub.6 -alkoxy, C.sub.5 -C.sub.7 -cycloalkyl, aryl, aryloxy, C.sub.1
-C.sub.6 -alkylamino and arylamino; R.sub.1 is selected from hydrogen,
C.sub.1 -C.sub.6 -alkyl, C.sub.1 -C.sub.6 -alkoxy and halogen; R.sub.2 is
hydrogen or methyl; and R.sub.3 is a covalent bond or is selected from a
group of the formulae --(CHR').sub.n --, --O--, --S--, --C(O)--,
--OC(O)--, --C(O)O--, --C(O)--O(CH.sub.2).sub.n --O--C(O)--, and
--NH--C(O)--, wherein R' is hydrogen or a group of the formula
R--C(O)O-phenyl- or R--C(O)O--naphthyl-; each R" is hydrogen or both R"
are taken together to form a group of the formula
##STR3##
and n is an integer of from 1 to 10; (b) about 0 to about 50 wt % of a
styrene compound of Formula B, and/or an acylated vinyl alcohols of
Formula C,
##STR4##
wherein R, R.sub.1 and R.sub.2 are as defined above; (c) about 20 to about
90 wt % of an acrylate monomer of Formula D,
##STR5##
wherein R.sub.2 is as defined above and R.sub.4 is selected from C.sub.1
-C.sub.12 -alkyl; C.sub.5 -C.sub.7 -cycloalkyl; c.sub.1 -C.sub.12 -alkyl
substituted by one or more groups selected from C.sub.1 -C.sub.6 -alkoxy,
C.sub.5 -C.sub.7 -cycloalkyl, hydroxy, acetoacetoxy, aryl, furyl,
tetrahydofuryl and --N(R.sub.5)R.sub.6 wherein R.sub.5 and R.sub.6 are
independently selected from C.sub.1 -C.sub.6 -alkyl or hydrogen; and
(d) about 0 to about 20 wt % of acrylic acid and/or methacrylic acid, the
total of (a), (b), (c) and (d) being 100%,
said polymerization folowed by transesterification with an alcohol to
convert acyloxyphenyl groups on the polymer to the phenol functionalized
vinyl polymer;
(II) about 5 to about 20 wt % of an amino crosslinking agent, based on the
total weight of I, II and III; and
(III) about 20 to about 70 wt % of an organic solvent, based on the total
weight of (I), (II) and (III), the total of (I), (II), and (III) being
100%.
As a further aspect of the present invention, there is provided a water
borne enamel composition comprising
(I) about 25 to about 65 wt %, based on the total weight of components (I),
(II), (III), (IV) and (V), of a phenol functionalized vinyl polymer having
a number average molecular weight of about 1000 to about 50,000 and a
weight average molecular weight of about 5,000 to about 100,000, said
phenol functionalized vinyl polymer prepared by polymerization of the
following vinyl components:
(a) about 5 to about 80 wt % of a 4-acyloxystyrene compound of Formula A,
##STR6##
wherein R is selected from hydrogen, C.sub.1 -C.sub.6 -alkyl, C.sub.1
-C.sub.6 -alkoxy, C.sub.5 -C.sub.7 -cycloalkyl, aryl, aryloxy, C.sub.1
-C.sub.6 -alkylamino and arylamino; R.sub.1 is selected from hydrogen,
C.sub.1 -C.sub.6 -alkyl, C.sub.1 -C.sub.6 -alkoxy and halogen; R.sub.2 is
hydrogen or methyl; and R.sub.3 is a covalent bond or is selected from a
group of the formulae --(CHR').sub.n --, --O--, --S--, --C(O)--,
--OC(O)--, --C(O)O--, --C(O)--O(CH.sub.2).sub.n --O--C(O)--, and
--NHC(O)--, wherein R' is hydrogen or a group of the formula
R--C(O)O-phenyl-, or R--C(O)O-naphthyl, each R" is hydrogen or both R" are
taken together to form a group of the formula
##STR7##
and n is an integer of from 1 to 10; (b) about 0 to about 50 wt % of a
styrene compound of Formula B, and/or an acylated vinyl alcohol of Formula
C,
##STR8##
wherein R, R.sub.1 and R.sub.2 are as defined above; (c) about 20 to
about 90 wt % of an acrylate monomer of Formula D,
##STR9##
wherein R.sub.2 is as defined above and R.sub.4 is selected from C.sub.1
-C.sub.12 -alkyl; C.sub.5 -C.sub.7 -cycloalkyl; C.sub.1 -C.sub.12 -alkyl
substituted by one or more groups selected from C.sub.1 -C.sub.6 -alkoxy,
C.sub.5 -C-cycloalkyl, hydroxy, acetoacetoxy, aryl, furyl, tetrahydofuryl
and --N(R.sub.5)R.sub.6 wherein R.sub.5 and R.sub.6 are independently
selected from C.sub.1 -C.sub.6 -alkyl or hydrogen; and
(d) about 0 to about 20 wt % of acrylic acid and/or methacrylic acid,
said polymerization followed by tranesterification with an alcohol to
convert the acyloxyphenyl groups on the polymer to the phenol
functionalized vinyl polymer (I);
(II) about 0 to about 30 wt % of a water-miscible organic solvent, based on
the total weight of I, II, III, IV and (V);
(III) about 30 to about 70 wt % of water, based on the total weight of (I),
(II), (III), (IV) and (V);
(IV) about 5 to about 20 wt % of a crosslinking agent, based on the total
weight of (I), (II), (III), (IV) and (V);
(V) about 0.5 to about 3 wt % of an amine, based on the total weight of
(I), (II), (III), (IV), and (V), wherein said amine is reacted directly
with said vinyl polymer (I).
In an especially preferred embodiment of the present invention, in the
compound of formula (A), R.sub.3 is a covalent bond or is selected from a
group of the formulae --(CHR').sub.n --, --O--, --S--, --C(O)--, and
--OC(O)--, wherein R' is hydrogen or a group of the formula
R--C(O)O-phenyl- and n is an integer of from 1 to 10.
As used herein, the term "acyl" is used to include the reactive residues of
carboxylic acids, carboxylic acid esters, carboxylic acid halides,
carboxylic acid anhydrides and isothoscyanates, for example, formyl,
acetoacetyl, C.sub.1 -C.sub.6 -alkylaminocarbonyl, C.sub.5 -C.sub.7
-cycloalkylcarbonyl, aroyl (arylcarbonyl), aroyloxycarbonyl and
arylaminocarbonyl. The preferred "acyl" group is C.sub.1 -C.sub.6
-alkylcarbonyl, especially acetyl.
In the terms "C.sub.1 -C.sub.6 -alkyl" and "C.sub.1 -C.sub.8 alkyl" the
alkyl groups may optionally contain one to three substituents selected
from hydroxy, halogen, C.sub.1 -C.sub.6 -alkoxy, aryl, C.sub.1 -C.sub.6
-cycloalkyl, cyano, etc.
Examples of groups within the term "aryl" include phenyl, 2(3) furyl and
2(3) thienyl and such groups containing one to three substituents selected
from C.sub.1 -C.sub.6 -alkyl, C.sub.1 -C.sub.6 -alkoxy, or halogen.
The term "C.sub.5 -C.sub.7 -cycloalkyl" is used to include cyclopentyl,
cyclohexyl, cycloheptyl and such groups substituted one to three times
with C.sub.1 -C.sub.6 -alkyl, C.sub.1 -C.sub.6 -alkoxy or halogen.
Preferred process steps for providing the hydroxy functionalized vinyl
polymer are as follows:
(a) reacting a mixture comprising one or more 4-acyloxystyrenes, one or
more acrylate esters, and optionally one or more styrene or vinyl acrylate
comonomers, in the presence of a free radical initiator and
(b) subsequently transesterifying the acyloxy groups present on the vinyl
polymer thus produced in (a) by reacting with alcohols to produce the
desired phenol functionalized resins.
Various types of free radical initiators are known in the art such as
peroxides, e.g., benzoyl peroxide, persulfates, e.g., sodium persulfate,
perborates, permanganates and aliphatic azo compounds, e.g.,
azobis-isobutyronitrile and 2,2' azobis(2,4-dimethyl valeronitrile, and
the like, which are widely used.
The tranesterification step (b) may be conveniently carried out by treating
the polymer prepared in step (a) with one or more alcohols which provide
an acceptable transesterification rate; primary alcohols are preferred.
Transesterification catalysts may also be used to facilitate the reaction.
Typical catalysts include organic sulfonic acids, e.g., p-toluene sulfonic
acid, butylstannoic acid, titanium alkoxides, e.g., titanium
tetraisopropoxide, acylated zinc hydroxides, e.g., zinc acetate, etc. It
is preferred that primary C.sub.1 -C.sub.6 -alcohols are used and that the
reaction be done under atmospheric pressure; however, with the more
volatile alcohols such as methanol, pressure reactors may be employed as
needed to achieve the desired temperature and rate of transesterification.
In one desirable modification, the transesterification step (b) is
accomplished in the same alcohol present in step (a). The transformation
of aceloxyphenyl groups into hydroxyphenyl groups is evidenced by analysis
of the infrared spectra.
Although the vinyl polymerization may be carried out in a variety of polar
solvents including alcohols, ketones, e.g., methyl ethyl ketone and methyl
n-amyl ketone, CELLOSOLVES.TM., e.g., methyl Cellosolve (2-methoxyethanol)
and cyclic ethers such as 1,4-dioxane and tetrahydrofuran, alcohols are
preferred and butanols are particularly preferred. Non polar solvents such
as toluene, xylene, cyclohexane, hexane and heptane may also be present,
preferably at less than 25% by weight of the reaction mixture.
The molecular weight of the polymer in step (a) is controlled by the
presence of small amounts of chain transfer agents such as alkyl
mercaptans. Also, the polar solvents used, particularly the alcohols or
tetrahydrofuran, may serve as chain transfer agents.
Typically, styrene compounds of Formula B include styrene, .alpha.-methyl
styrene, 4-isopropyl styrene, 2- ,3- or 4-methylstyrene, 2- ,3- or
4-chlorostyrene and 2- ,3- or 4-methoxystyrene and styrene itself is
especially preferred.
Typical acylated vinyl alcohols of Formula C above include vinyl acetate,
vinyl propionate, vinyl butyrate, 2-ethyl cyanate, vinyl pivalate
(available from Unin Carbide Co.), and the like. Vinyl acetate is highly
preferred.
Examples of preferred acrylate esters of Formula D include methyl acrylate,
methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate,
n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, benzyl
acrylate, 4 methyl benzyl methacrylate, furyl acrylate, methyl furyl
acetate, 2-(2-thienyl) ethyl acrylate, n-hexyl acrylate, isoamyl
methacrylate, 2-(hydroxyethyl) acrylate, 2-(hydroxyethyl) methacrylate,
3-(hydroxypropyl) methacrylate, 2-(ethoxyethyl) acrylate, 2-(methoxyethyl)
methacrylate, glycidyl methacrylate, 2-ethylhexyl acrylate, cyclopentyl
acrylate, cylohexylmethyl methacrylate, cyclohexyl methacrylate, lauryl
acrylate, lauryl methacrylate, stearyl methacrylate, stearyl acrylate,
octyl acrylate, octyl methacrylate, tetrahydrofurfuryl acrylate, furfuryl
methacrylate, 2-(acetoxyethyl) acrylate, 3-(acetoxypropyl) methacrylate,
2-(dimethylaminoethyl) acrylate, 3-(dimethylaminopropyl) methacrylate,
acetoacetoxyethyl acrylate, acetoacetoxyethyl methacrylate,
aceto-acetoxypropyl acrylate, and acetoacetoxypropyl methacrylate.
In the preparation of the water-borne enamel compositions above, the
curable acrylic polymer is treated directly with an amine to render the
resin water dispersible. Typical amines include ammonia, triethylamine,
diethylamine, monoethanolamine, monoisopropanolamine, morpholine,
ethanolamine, diethanolamine, triethanolamine, N,N-dimethyl ethanolamine,
N,N-diethyl ethanolamine, N-methyl-diethanolamine and the like. As noted
above, the curable acrylic resins of the present invention possess phenol
functional groups which are sufficiently acidic to react directly with the
amine. However, resins with a carboxylic acid number of 20-40 mg KOH/g are
preferred. The acid number of the resins may be controlled by the amount
of acrylic acid and/or methacrylic acid resin used in the formulations.
The conventional carboxyl-enrichment-amine-neutralization method has
already been described by others in considerable detail (see, for example,
Olding and Hayward, Ed., "Resins for Surface Coatings", Volume III, SITA
Technology, London, 1987, p 182).
It will be appreciated, of course, that in the above description and as
described below, the various mole and weight percentages in the
compositions herein will always total 100 percent.
Suitable solvents for the curable enamel composition include xylenes,
cyclohexanone, ketones, (for example, methyl amyl ketone),
2-butoxyethanol, ethyl-3-ethoxypropionate (EEP), toluene, n-butanol, and
other volatile inert solvents typically used in industrial baking (i.e.,
thermosetting) enamels.
Suitable co-solvents for the water-borne compositions of the present
invention include ethanol, n-propanol, isopropanol, n-butanol,
sec-butanol, isobutanol, ethylene glycol monobutyl ether, propylene glycol
n-butyl ether, propylene glycol methyl ether, propylene glycol monopropyl
ether, dipropylene glycol methyl ether, diacetone alcohol, and other
water-miscible solvents.
The "amino cross-linking agent" is preferably a melamine-formaldehyde type
cross-linking agent, i.e., a cross-linking agent having a plurality of
--N(CH.sub.2 OR.sup.3).sub.2 functional groups, wherein R.sup.3 is C.sub.1
-C.sub.4 alkyl or hydrogen, preferably methyl.
The cross-linking agent may also be a modified melamine-formaldehyde type
resin such as toluene sulfonamide modified melamine-formaldehyde resins,
and the like.
In general, the cross-linking agent may be selected from compounds of the
following formulae, wherein R.sup.3 is independently C.sub.1 -C.sub.4
alkyl or hydrogen:
##STR10##
In this regard, preferred cross linking agents include
hexamethoxymethylmelamine, tetramethoxymethylbenzoguanamine,
tetramethoxymethylurea, mixed butoxy/methoxy substituted melamines, and
the like. The most preferred cross linking agent is
hexamethoxymethylmelamine.
As a further aspect of the present invention, there is provided a curable
enamel composition further comprising one or more cross-linking catalysts.
Examples of such catalysts include p-toluenesulfonic acid, the NACURE.TM.
155, 5076, 1051, 5225, 4167, and 2547 catalysts sold by King Industries,
BYK.RTM. Catalyst 450, 470, available from BYK-Chemie U.S.A., methyl tolyl
sulfonimide, and the like.
As a further aspect of the present invention there is provided a
cross-linkable enamel composition as described above, further comprising
one or more leveling, rheology, and flow control agents such as silicones,
fluorocarbons or cellulosics; flatting agents; pigment wetting and
dispersing agents; surfactants; ultraviolet (UV) absorbers; UV light
stabilizers; tinting pigments; defoaming and antifoaming agents;
anti-settling, anti-sag and bodying agents; anti-skinning agents;
anti-flooding and anti-floating agents; fungicides and mildewicides;
corrosion inhibitors; thickening agents; or coalescing agents.
Specific examples of such additives can be found in Raw Materials Index,
published by the National Paint & Coatings Association, 1500 Rhode Island
Avenue, N.W., Washington, D.C. 20005.
Examples of flatting agents include synthetic silica, available from the
Davison Chemical Division of W.R. Grace & Company under the trademark
SYLOID.RTM.; polypropylene, available from Hercules Inc., under the
trademark HERCOFLAT.RTM.; synthetic silicate, available from J.M. Huber
Corporation under the trademark ZEOLEX.RTM..
Examples of dispersing agents and surfactants include sodium bis(tridecyl)
sulfosuccinnate, di(2-ethyl hexyl) sodium sulfosuccinnate, sodium
dihexylsulfosuccinnate, sodium dicyclohexyl sulfosuccinnate, diamyl sodium
sulfosuccinnate, sodium diisobutyl sulfosuccinnate, disodium iso-decyl
sulfosuccinnate, disodium ethoxylated alcohol half ester of sulfosuccinnic
acid, disodium alkyl amido polyethoxy sulfosuccinnate, tetrasodium N-(1,2
dicarboxy-ethyl)-N-octadecyl sulfosuccinnamate, disodium
N-octasulfosuccinnamate, sulfated ethoxylated nonylphenol,
2-amino-2-methyl-1-propanol, and the like.
Examples of viscosity, suspension, and flow control agents include
polyaminoamide phosphate, high molecular weight carboxylic acid salts of
polyamine amides, and alkyl amine salt of an unsaturated fatty acid, all
available from BYK Chemie U.S.A. under the trademark ANTI TERRA.RTM..
Further examples include polysiloxane copolymers, polyacrylate solution,
cellulose esters, hydroxyethyl cellulose, hydrophobically-modified
hydroxyethyl celuulose, hydroxypropyl cellulose, polyamide wax, polyolefin
wax, carboxymethyl cellulose, ammonium polyacrylate, sodium polyacrylate,
and polyethylene oxide.
Several proprietary antifoaming agents are commercially available, for
example, under the trademark BRUBREAK of Buckman Laboratories Inc., under
the BYK.RTM. trademark of BYK Chemie, U.S.A., under the FOAMASTER.RTM. and
NOPCO.RTM. trademarks of Henkel Corp./Coating Chemicals, under the
DREWPLUS.RTM. trademark of the Drew Industrial Division of Ashland
Chemical Company, under the TROYSOL.RTM. and TROYKYD.RTM. trademarks of
Troy Chemical Corporation, and under the SAG.RTM. trademark of Union
Carbide Corporation.
Examples of fungicides, mildewicides, and biocides include
4,4-dimethyloxazolidine, 3,4,4-trimethyloxazolidine, modified barium
metaborate, potassium N-hydroxy-methyl-N-methyldithiocarbamate,
2-(thiocyanomethylthio) benzothiazole, potassium dimethyl dithiocarbamate,
adamantane, N-(trichloromethylthio) phthalimide,
2,4,5,6-tetrachloroisophthalonitrile, orthophenyl phenol,
2,4,5-trichlorophenol, dehydroacetic acid, copper naphthenate, copper
octoate, organic arsenic, tributyl tin oxide, zinc naphthenate, and copper
8-quinolinate.
Examples of U.V. absorbers and U.V. light stabilizers include substituted
benzophenones, substituted benzotriazoles, hindered amines, and hindered
benzoates, available from American Cyanamid Company under the tradename
Cyasorb UV, and available from Ciba Geigy under the tradename Tinuvin, and
diethyl-3-acetyl-4-hydroxy-benzyl-phosphonate, 4-dodecyloxy-2-hydroxy
benzophenone, and resorcinol monobenzoate.
Such paint or coating additives as described above form a relatively minor
proportion of the enamel composition, preferably about 0.05 weight % to
about 5.00 weight %.
As a further aspect of the present invention, there is provided a curable
enamel composition optionally containing one or more of the
above-described additives, further comprising one or more pigments.
Pigments suitable for use in the enamel compositions envisioned by the
present invention are the typical organic and inorganic pigments,
well-known to one of ordinary skill in the art of surface coatings,
especially those set forth by the Colour Index, 3d Ed., 2d Rev., 1982,
published by the Society of Dyers and Colourists in association with the
American Association of Textile Chemiss and Colorists. Examples include
but are not limited to the following: CI Pigment White 6 (titanium
dioxide); CI Pigment Red 101 (red iron oxide); CI Pigment Yellow 42, CI
Pigment Blue 15, 15:1, 15:2, 15:3, 15:4 (copper phthalocyanines); CI
Pigment Red 49:1, and CI pigment Red 57:1.
Upon formulation as described above, the curable enamel composition is then
applied to the desired substrate or article, e.g., steel, aluminum, or
galvanized sheeting (either primed or unprimed), heated (i.e., cured) to a
temperature of about 130.degree. C. to about 175.degree. C., for a time
period of 5-60 minutes and subsequently allowed to cool. Thus, as a
further aspect of the present invention, there is provided a shaped or
formed article which has been coated with the thermo-setting coating
compositions of the present invention and cured.
Further examples of typical application and curing methods can be found in
U.S. Pat. Nos. 4,737,551 and 4,698,391, incorporated herein by reference.
As a further aspect of the present invention, there is provided a coating
which results from the application and curing of the curable enamel
composition as set forth above.
The following examples illustrate further the practice of the invention.
EXPERIMENTAL SECTION
Example 1--Polymerization of Vinyl Monomers
In a 500 mL round-bottom flask equipped with a water condenser were mixed
with stirring the following compounds: methyl methacrylate (25 g), n-butyl
acrylate (25 g), styrene (25 g), 4-acetoxystyrene (26.1 g),
tert-dodecanethiol (0.2 g), and n-butanol (90 g). The mixture was then
heated to about 100.degree. C. and the stirring continued. A solution of
initiator, azobisisobutyronitrile (AIBN) (2.0 g), dissolved in n-butanol
(10 g) was prepared. This initiator suspension was added sequentially to
the reaction mixture every 0.5 hr in three portions. The polymerization
was complete after refluxing at 100.degree. C. for four hours by
determining the percent solids of the reaction mixture. The resulting
resin solution turned white upon cooling.
Example 2--Transesterification of Acetoxyphenl Groups on the Resin of
Example 1
To a portion (100 g) of the above resin solution was added FASCAT 4100
catalyst (0.1 g) (Atochem North America, Inc.) and the mixture refluxed at
110.degree. C. for 15 hours to complete the transesterification. To this
mixture was added xylnne (20 g) and the temperature raised to 135.degree.
C. in order to distill off about 50 mL of the solvents. The resulting
resin 1 was collected and determined to have 66% solids.
Example 3--Synthesis of Resin 2
In a 500 mL round bottom flask equipped with a water condenser were mixed
with stirring the following compounds: methyl methacrylate (25 g), n-butyl
acrylate (25 g), styrene (25 g), 4-acetoxystyrene (13 g), 2-hydroxyethyl
methacrylate (9 g), tert-odecanethiol (0.2 g), and n-butanol (85 g). The
mixture was then heated to about 100.degree. C. and the stirring
continued. A solution of initiator, azobisisobutyronitrile (AIBN) (3.0 g),
dissolved in n-butanol (15 g) was prepared. This initiator suspension was
added sequentially to the reaction mixture every 0.5 hour in three
portions. The polymerization was complete after refluxing at 100.degree.
C. for three hours by determining the percent solids of the reaction
mixture.
To the above resin solution was added FASCAT 4100 (0.2 g) and the mixture
refluxed at 110.degree. C. for 15 hours to complete the
transesterification. To this mixture was added xylene (40 g) and the
temperature raised to 135.degree. C. in order to distill off about 123 mL
of the solvents. The resulting resin 2 was collected and determined to
have about 70% solids.
Example 4--Synthesis of Resin 3
In a 500 mL round bottom flask equipped with a water condenser were mixed
with stirring the following compounds: methyl methacrylate (53 g), n-butyl
acrylate (17 g), 4-acetoxystyrene (26 g), tert-dodecanethiol (0.2 g), and
n-butanol (85 g). The mixture was then heated to about 100.degree. C. and
the stirring continued. A solution of initiator, azobisisobutyronitrile
(AIBN) (3.0 g), dissolved in n-butanol (15 g) was prepared. This initiator
suspension was added sequentially to the reaction mixture every 0.5 hour
in three portions. The polymerization was complete after refluxing at
100.degree. C. for four hours by determining the percent solids of the
reaction mixture.
To the above resin solution was added FASCAT 4100 catalyst (0.2 g) and the
mixture refluxed at 110.degree. C. for 15 hours to complete the
transesterification. To this mixture was added methyl n-amyl ketone (MAK)
(43 g) and the temperature raised to 135.degree. C. in order to distill
off about 123 mL of the solvents. The resulting resin 2 was collected and
determined to have about 70% solids.
Example 5--Synthesis of Control Resin 1
In a 500 mL round-bottom flask equipped with a water condenser were mixed
with stirring the following compounds: methyl methacrylate (25 g), n-butyl
acrylate (25 g), styrene (29.2 g), 2-hydroxyethyl methacrylate (18.6 g),
tert-dodecanethiol (0.2 g), and methyl n-amyl ketone (MAK) (96 g). The
mixture was then heated to about 100.degree. C. and the stirring
continued. A solution of initiator, azobisisobutyronitrile (AIBN) (2.0 g),
dissolved in MAK (10 g) was prepared. This initiator suspension was added
sequentially to the reaction mixture every 0.5 hour in three portions. The
polymerization was complete after refluxing at 140.degree. C. for three hr
by determining the percent solids of the reaction mixture. About 71 mL of
the solvent was then distilled off at 155.degree. C. to give a resin with
about 70% solids.
Example 6--Synthesis of Control Resin 2
In a 500 mL round-bottom flask equipped with a water condenser were mixed
with stirring the following compounds: methyl methacrylate (15 g), n-butyl
acrylate (15 g), styrene (48 g), 2-hydroxyethyl methacrylate (19 g),
tert-dodecanethiol (0.2 g), and methyl n-amyl ketone (MAK) (85 g). The
mixture was then heated to about 100.degree. C. and the stirring
continued. A solution of initiator, azobisisobutyronitrile (AIBN) (3.0 g),
dissolved in MAK (15 g) was prepared. This initiator suspension was added
sequentially to the reaction mixture every 0.5 hour in three portions. The
polymerization was complete after refluxing at 110.degree. C. for three
hours by determining the percent solids of the reaction mixture. About 72
mL of the solvent was then distilled off at 160.degree. C. to give a resin
with about 70% solids.
Example 7--Preparation of Enamels
Enamels were prepared by adding the following components to 14.3 g of the
various resins (70% solids): CYMEL 303 (American Cyanamid Co.) 2.5 g,
NACURE 5076 (King Industries) 0.36 g, FLUORAD FC 430 (3M Co.) (20% in
isopropanol) 0.2 g, and a solvent blend (methyl n-amyl
ketone/xylene/EKTAPRO EEP (ethyl-3-ethoxy-propionate) (Eastman Chemical
Co.)=70/15/15 by weight) 10 g. The mixtures were then agitated well to
provide clear solutions.
Example 8--Preparation of Coatings
Coatings were prepared by applying various enamels to cold-rolled steel
test panels (ACT 3.times.9.times.032 from Advanced Coating Technologies)
and baking in an oven at 130.degree. C. for 30 minutes. The thickness of
the coating films was about 1.0 to 1.5 mil. The properties of various
resins and coatings are listed in Table I and II. Molecular weights were
estimated by gel permeation chromatography. Acid-etch resistance of the
coatings was tested by adding a few drops of 10% sulfuric acid (e.g. six
drops) onto the film surface of the coated panel and baking in an oven at
50.degree. C., 60.degree. C. or 70.degree. C. for 0.5 hour. Other coating
testings were carried out according to the following standard methods:
1. Film Thickness (Fisher Deltascope MP 2)
2. Solvent Resistance (MEK Double Rub, ASTM D1308)
3. Gloss (BYK-micro-gloss, ASTM D523)
4. Pencil Hardness (ASTM D3362)
5. Impact Resistance (BYK-Gardner Impact Tester, ASTM D2794)
TABLE I
__________________________________________________________________________
Resin Properties
RESIN
RESIN RESIN
CONTROL CONTROL
PROPERTY
1 2 3 1 2
__________________________________________________________________________
Mn 3800 3500 6700 1300 1400
Mw 23,000
19,000
25,000
48,000 17,000
Tg (.degree.C.)
72 45 41 42 70
__________________________________________________________________________
Mn: number average molecular weight
Mw: weight average molecular weight
Tg: glass transition temperature
TABLE II
__________________________________________________________________________
Coating Properties
PROPERTIES ENAMEL 1
ENAMEL 2
ENAMEL 3
CONTROL 1
CONTROL 2
__________________________________________________________________________
MEK double rubs
>200 >200 >200 >200 >200
gloss, 60.degree./20.degree.
100/95 99/95 97/86 99/91 103/94
hardness 4H H H 4H H
Impact resistance
20/<20 <20/<20
<20/<20
20/<20 20/<20
direct/reverse (lb-in.)
10% H.sub.2 SO.sub.4, 50.degree. C.
no effect
no effect
no effect
loss of gloss
loss of gloss
10% H.sub.2 SO.sub.4, 60.degree. C.
no effect
blistering
blistering
loss of gloss
loss of gloss
film film
decomposed
decomposed
10% H.sub.2 SO.sub.4, 70.degree. C.
no effect
-- -- -- --
__________________________________________________________________________
Example 9--Synthesis of Water borne Resin
In a 500 mL round-bottom flask equipped with a water condenser were mixed
with stirring the following compounds: methyl methacrylate (25 g), n-butyl
acrylate (25 g), styrene (20 g), 4-acetoxystyrene (25 g), acrylic acid
(2.57 g), tert-dodecanethiol (0.4 g), and n-butanol (85 g). The mixture
was then heated to about 100.degree. C. and the stirring continued. A
solution of initiator, azobisisobutyronitrile (AIBN) (4.0 g), dissolved in
n-butanol (15 g) was prepared. This initiator suspension was added
sequentially to the reaction mixture every 0.5 hour in three portions. The
polymerization was complete after refluxing at 100.degree. C. for four
hours by determining the percent solids of the reaction mixture.
To the above resin solution was added FASCAT 4100 catalyst (0.2 g) and the
mixture refluxed at 11020 C. for 15 hours to complete the
transesterification. To this mixture was added ethylene glycol monobutyl
ether (EB) (43 g) and the temperature raised to 135.degree. C. in order to
distill off about 123 mL of the solvents. The resulting resin was
collected and determined to have 67% solids.
Example 10--Preparation of Water-borne Enamel
To 14.9 g of the above resin (67% solids in EB) were added
N,N-dimethylethanolamine (DMEA) (0.66 g) and distilled water (33 g). The
mixture was stirred to give an aqueous dispersion. To this dispersion were
added Cymel 303 (2.5 g) and FLUORAD FC 430 (20% in isopropanol, 0.2 g) to
yield a water borne enamel. The enamel was applied onto test panels and
cured at 175.degree. C. for 30 min. The coating showed the following
properties: gloss (60.degree./20.degree.), 99/86; pencil hardness, 4H;
impact resistance (direct/reverse), 40/<20; acid-etch resistance,
50.degree. C.--no effect, 60.degree. C.--blistering.
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